The present invention relates generally to the testing of fiber samples and, more particularly, to apparatus for individualizing single fibers and other entities in textile fiber samples for testing purposes.
Testing of fiber samples, such as, but not limited to, cotton, is important for determining the market value of a particular batch of material, as well as for determining a suitable usage and what processing may be required in gins or spinning mills. Today, nearly 100% of the cotton grown in the United States is classed employing testing instruments. Testing includes determining such characteristics as fiber length, as well as the content of undesired textile entities such as trash and neps.
As a relatively early example, a comb-like device for preparing a sample of ginned cotton for measuring the fiber length thereof is disclosed in Hertel U.S. Pat. No. 2,404,708, which issued in 1946. That same inventor later developed what is now known as a Hertel needle sampler, disclosed in Hertel U.S. Pat. No. 3,057,019. The Hertel needle sampler is a comb-like device arranged for movement past a perforated plate which has a fibrous mass pushed against the opposite side so that portions of the fibrous mass protrude through the perforations and are loaded onto the needles. A screw-thread based locking device then retains the fibers on the needle sampler, forming what is known in the art as a tapered beard because the fibers are of varying lengths. The tapered beard is prepared by combing and brushing to parallelize the fibers, as well as to remove loose fibers. Automated versions of the Hertel needle sampler have been developed.
The tapered beard is then subjected to analysis. For example, an instrument known as a Fibrograph is employed to optically determine various characteristics of the tapered beard, including the profile along its length. In addition, a separate test may be made of the strength of the tapered beard.
In some respects, the sample as taken by a Hertel needle sampler and the measurement of length and strength therefrom, are worldwide standards.
The Hertel needle sampler approach involves collectively testing, essentially simultaneously, all of the fibers of a sample, assumed to be a representative sample.
An alternative approach is to individualize and test single fibers and other textile entities, for example neps and trash. Testing single fiber entities can provide a better analysis.
However, such an approach conventionally requires that entities be individualized and fed one at a time into suitable analysis means for testing. A device for such individualizing is generally termed a "fiber individualizer," and is generally so termed herein, although a more precise term is "entity individualizer" since, for purposes of testing, it is necessary to accurately determine the amount of neps and trash in a particular sample, in addition to characteristics of the fibers themselves.
An example of such single entity testing apparatus is disclosed in Shofner U.S. Pat. Nos. 4,512,060 and 4,686,744, which disclose what is termed in those patents a microdust and trash machine (MTM), and what has since become known as an advanced fiber information system (AFIS), currently manufactured by Zellweger Uster, Inc. in Knoxville, Tennessee.
In one form, the AFIS machine separates fibers and neps into one airstream, and trash into another air stream. Optical-based sensors then measure the individual entitles. Individual entities can be analyzed at rates as high as 1000 per second. An AFIS more particularly includes an aeromechanical separator or fiber individualizer; high speed entity sensors; and a high information rate computer for data collection and analysis.
Improvements to the AFIS, particularly improved sensors where a single sensor analyzes neps, trash and fibers individualized all in one air stream are disclosed in Shofner et al U.S. Pat. No. 5,270,787, titled "Electro-Optical Methods and Apparatus for High Speed, Multivariate Measurement of Individual Entities in Fiber or Other Samples;" in Shofner et al U.S. Pat. No. 5,321,496, titled "Apparatus for Monitoring Trash in a Fiber Sample;" and in Shofner et al U.S. Pat. No. 5,469,253, titled "Apparatus and Method for Testing Multiple Characteristics of Single Textile Sample with Automatic Feed."
The fiber individualizer portion of an AFIS, such as is disclosed in U.S. Pat. Nos. 4,512,060 and 4,686,744, includes a cylindrical rotating beater wheel having projections which engage fibers of fibrous material fed to the beater wheel for testing. The beater wheel rotates at typically 7,500 rpm, which a circumferential velocity of 5,000 FPM, and is similar to the licker-in of a conventional carding machine, or the beater stage of an open-end spinning head, with the exception that the AFIS beater wheel includes perforations which allow radially inward airflow.
The perforations in the prior art beater wheel and, more particularly, the radially inward air flow through the perforations, is significant in that it causes the fibers to engage the pins on the rotating beater wheel. If fiber is merely presented to a rotating beater wheel, the fiber tends to run away and not engage. As a result, the entities are not individualized well, neps are produced, and trash is not removed as efficiently.
While quite effective, a rotating perforated cylinder, normally also requiring a stationary shoe inside connected to a vacuum source for drawing air radially in through the perforations, is a relatively expensive device to manufacture.
Conventional practice, particularly in processing operations, is to simply present fiber to a rotating beater wheel, typically from a feed roller, with no particular air flow introduced at all. This approach suffers the disadvantages that it does not individualize well, neps are produced and trash is not removed effectively.